AB0736 EPIDEMIOLOGY OF CLINICALLY ISOLATED AORTITIS: A POPULATION-BASED STUDY
Authors: M. Kaymakci, M. Elfishawi, H. Langenfeld, C. S. Crowson, W. Cornelia, M. Koster, K. J. Warrington
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Clinically isolated aortitis (CIA) refers to inflammation of the aorta without signs of systemic vasculitis or infection [1]. The diagnosis of CIA generally relies on histopathologic evaluation of aortic tissue obtained during thoracic aortic aneurysm surgery making the diagnosis more challenging. Recent studies suggest that CIA might be a limited presentation of giant cell arteritis [2]. Population-based data on the epidemiology of CIA in North America is lacking. <h3>Objectives</h3> The objectives of this study were to evaluate the epidemiology, clinical characteristics, and outcomes of patients with CIA. <h3>Methods</h3> In a defined geographical area, all possible subjects were screened for thoracic aortic aneurysm procedures with current procedural terminology (CPT) codes between January 1, 2000, and December 31, 2021. The medical records of all patients were manually reviewed. CIA was defined as histopathologically confirmed active aortitis diagnosed by evaluation of aortic tissue obtained during thoracic aortic aneurysm surgery in the absence of any infection, rheumatic disease, or systemic vasculitis. Incidence rates were age and sex adjusted to the 2020 United States total population. Mortality rates were estimated using the Kaplan-Meier method and were compared with expected mortality rates for persons of the same age, sex, and calendar year estimated using Minnesota population life tables. <h3>Results</h3> Eight incident cases of CIA were diagnosed during the study period (Figure 1); 6 (75%) of them were female. Median (IQR) age at diagnosis of CIA was 78.3 (70.2- 78.9) years; all were diagnosed following ascending aortic aneurysm repair. The overall age and sex adjusted annual incidence rate of CIA was 8.9 (95% CI, 2.7- 15.1) per 1,000,000 individuals over age 50 years. Histopathological evaluation demonstrated giant cell aortitis in 7 (88%) patients and lymphoplasmacytic aortitis in 1 (13%) patient. Five (63%) patients were seen by a rheumatologist and 2 (25%) were treated with glucocorticoids after the diagnosis of CIA. Most of the patients had cardiovascular signs and symptoms prior to the surgery. One patient presented with aortic dissection and contained rupture. The median (IQR) duration of follow-up was 8.7 (1.2- 12.0) years. Five (63%) patients died during follow-up; 1 (13%) within one week of surgery. The overall mortality compared to the age and sex matched general population did not differ (standardized mortality ratio: 1.58; 95% CI, 0.51 3.68). <h3>Conclusion</h3> This is the first population-based epidemiologic study of CIA in North America. CIA predominantly affects older women and is quite rare. In this small cohort, survival following a diagnosis of CIA was not significantly different than the general population. <h3>References</h3> [1]Cinar I, Wang H, Stone JR. Clinically isolated aortitis: pitfalls, progress, and possibilities. <i>Cardiovasc Pathol</i> 2017;<b>29</b>:23–32. doi:10.1016/j.carpath.2017.04.003 [2]Hur B, Koster MJ, Jang JS, <i>et al.</i> Global Transcriptomic Profiling Identifies Differential Gene Expression Signatures Between Inflammatory and Noninflammatory Aortic Aneurysms. <i>Arthritis Rheumatol</i> 2022;<b>74</b>:1376–86. doi:10.1002/art.42138 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Mahmut Kaymakci: None declared, Mohanad Elfishawi: None declared, Hannah Langenfeld: None declared, Cynthia S. Crowson: None declared, Weyand Cornelia: None declared, Matthew Koster: None declared, Kenneth J Warrington Consultant of: Chemocentryx, Sanofi, Grant/research support from: Eli Lilly, Kiniksa, GSK.